The Millers played Greg Halford in front of the back four at Hillsbrough and upset the odds to win 1-0 as the utility man nullified the threat of Owls dangerman Barry Bannan.
“Bannan’s a good player at this level, I had him at Crystal Palace,” boss Warnock said. “Him and Kieran Lee are as good as anything if you let them be and they slide balls in.
“It was effective with Greg there because it ended up with Gary Hooper coming short almost into the midfield area instead of being on the shoulder of the centre-halves, so it was good tactics.
“We decided on Thursday to do that. I sat with (coaches) Kevin Blackwell and Ronnie Jepson, and that seemed to be the best way forward really. You have got to be a little bit versatile in the Championship.”
Rotherham remain three points away from safety, but have now recorded two successive victories ahead of tomorrow’s home clash with Middlesbrough.
Warnock joked about motivating his side for the test against Carlos Carvalhal’s promotion contenders.
“We didn’t want to defend, but a side like Wednesday do batter a lot of teams at home,” he said.
“I said to my boys before the game, the Owls have not lost at Hillsborough since August but the plus thing is, if you look at our last eight away from home, we have lost seven and drawn one, so that must give us chance!
“I think they thought I was telling the truth. I didn’t laugh.”
Meanwhile, goal hero Matt Derbyshire saluted the performance of lone striker Danny Ward.
Centre-forward Derbyshire, playing in an unfamiliar position wide on the left, make the breakthrough for the Millers in the 21st minute, but was quick to acknowledge man of the match Ward
“He’s brilliant. He works his socks off. He’s a very unselfish forward and he’s always happy for other people when they score,” he said.
“He’s fantastic to play with as well. It wasn’t just Danny, though. Everyone in the team performed, the lads who came on as well. It was great for everyone.
Rotherham weathered a second-half Owls onslaught to remain unbeaten at Hillsborough since 1981.
“You’re always going to come under pressure,” Derbyshire added.
“They were always going to have a big spell in the second half because they would have had a bit of telling-off at half-time. We were ready for that.
“It’s obviously difficult playing left-back when you’re a forward! But it’s not about me, it’s about the team and about this club staying in the Championship. This is another step forward to doing that.”